1. Field of the Invention
The invention relates to oral compositions, particularly to oral compositions containing an aminosilicone and a lipophilic compound.
2. Related Art
Plaque is initiated when bacteria adhered to pellicle form a proteinaceous film on the surface of teeth. The adherent bacteria metabolize dietary constituents and produce and aggregate to form the tenatious deposit known as plaque. Plaque generally consists of bacteria, bacterial end products such as polysaccharides, inorganic salts and salivary proteins. Plaque bacteria ferment dietary carbohydrates to organic acids which demineralize enamel resulting in tooth decay.
Calculus is essentially plaque that has been mineralized with calcium phosphates salts. As calculus matures and hardens, it tends to stain noticeably due to adsorption of dietary chromagens. In addition to their unattractive appearance, calculus deposits at the gum line are a contributing source of gingivitis and periodontal disease. Besides the hygienic and health problems resulting from plaque, research has shown that the primary source of bad breath is the retention and subsequent degradation of dead cellular material sloughed off continuously by the normal, healthy mouth.
Modern dental hygiene preparations typically contain antiplaque and/or antitartar agents, as well as antimicrobial agents and flavorants. Antimicrobial action could affect plaque formation by either reducing the number of bacteria in the mouth or by killing those bacteria trapped in the film to prevent further growth and metabolism. Flavorants may alleviate the problem of bad breath via a deodorizing action. Some antimicrobial agents, e.g. menthol may, also serve as breath deodorizers. However, the efficacy of antimicrobial agents depends largely on their intraoral retention, particularly their retention on the tooth surface where plaque and calculus are formed.
A typical disadvantage of known dental preparations is that only a relatively short time during which the teeth are being cleaned or the mouth is being rinsed is available for antimicrobial agents in the preparations to take effect. The problem is compounded by the fact that dentifrice preparations are used infrequently: most are used once or, perhaps, twice daily. Consequently, the long time period between brushings for a majority of the population provides optimum plaque forming conditions.
There has been a need, therefore, for developing an oral formulation which has a prolonged, residual effect.
It is known to include silicones in dentifrice compositions. It has been proposed in the art that silicones would coat teeth and thereby prevent cavities and staining. For instance, British patent specification 689,679 discloses a mouthwash containing an organopolysiloxane for the purpose of preventing adhesion of, or for removal of, tars, stains, tartar and food particles from the teeth. The mouthwash may include antiseptic compounds, such as thymol, and flavoring and perfuming agents. The mouthwash may be prepared by mixing the polysiloxane, alcohol and emulsifying agent, adding an antiseptic, and, subsequently, diluting the mixture with water.
U.S. Pat. No. 2,806,814 (Richter) discloses dental preparations including, in combination, a higher aliphatic acyl amide of an amino carboxylic acid compound as an active and a silicone compound. The patent notes that silicone compounds have been proposed for prevention of adhesion or to facilitate the removal of tars, stains, tartar and the like from teeth. The patent also claims that the silicone compound acts as a synergist in improving the antibacterial and acid inhibiting activity of the active ingredient. Dimethyl polysiloxanes are said to have been found to be particularly effective in the Richter invention. Flavoring oils and/or menthol may be included.
However, silicone polymers such as those disclosed in the '679 specification and in the Richter patent, have not generally been successfully used for coating the teeth since it has been found that the polysiloxane does not adhere to the teeth for a prolonged period of time.
Viccaro et al., copending application Ser. No. 07/276 704 filed Nov. 28, 1988 and entitled "Dentifrices Containing Aminoalkyl Silicones", discloses Dentifrice Formulations including aminoalkyl silicones for coating the teeth and inhibiting stain and caries. The '704 application demonstrates that amino-functional groups increase the substantivity of silicone based polymers, apparently due to the interaction of the positively charged nitrogen of the amine with the negative charges on the surface of the teeth. Example I of the '704 application illustrates that aminoalkyl silicones are more substantive to a pellicle-coated surface than dimethicones. The antistaining properties of the dentifrices are said to be of particular significance when the aminoalkyl silicones are used in conjunction with antimicrobials such as quaternary salts or bis biguanides such as chlorhexidine digluconate.
Although the compositions of the '704 application may contain an antimicrobial agent, the specific antimicrobial agents disclosed therein (i.e. quaternary ammonium compounds or a bis biguanide such as chlorhexidine digluconate) are water-soluble. By contrast, antimicrobials included in the present invention are lipophilic. Further in contrast to the present invention, the '704 application does not teach the presence of any lipophilic compound or any antimicrobial compound, along with an aminoalkyl silicone, in an oil phase of oil-in-water emulsions. The '704 application expresses the belief that the aminoalkyl silicones prevent the adhesion of staining materials such as chlorhexidine digluconate and, additionally, facilitate removal of the staining materials from the teeth. By contrast, the aminoalkyl silicones in the present invention are employed to enhance the adhesion of lipophilic compounds to the teeth surface.
U.S. Pat. No. 4,994,593 (Lin et al.) discloses a specific class of modified aminosilicones which have reduced reactivity but still retain positive charges over a broad pH range. The Lin et al. patent also embraces compositions employing the modified aminosilicones. Lin et al. teach that dentifrices which include their aminoalkyl silicones can be used to form a hydrophobic barrier on the surface of teeth which is used for prevention of staining of teeth and in preventing cavities. Like in the '704 application, the antistaining properties of dentifrices incorporating the modified aminosilicones of the Lin et al. patent are said to be of particular significance when the compounds of the patent are used in conjunction with an antimicrobial quaternary ammonium salt or biguanide such as chlorhexidine digluconate. Lin et al. teach that increasing the number of aminoalkyl groups per molecule enhances the substantivity of the silicone. Also, increasing the charge density improves substantivity as well. Dentifrices including the modified aminoalkyl silicones of the Lin et al. patent are disclosed in a greater detail in Lin et al. copending application, Ser. No. 07/276,719, filed Nov. 28, 1988, now U.S. Pat. No. 5,078,988.
U.S. Pat. No. 4,243,658, U.S. Pat. No. 4,304,766, U.S. Pat. No. 4,485,090, and U.S. Pat. No. 4,510,127 (all authored by Chang) disclose a dentifrice composition for substantially reducing elution of a previously applied therapeutic agent from teeth. The composition contains at least 0.05% by weight, preferably from about 0.1 to 5%, of a membrane-forming material which, when applied to the surface of teeth in an oral environment, forms a substantially continuous hydrophobic barrier thereon which substantially reduces the elution of the previously applied therapeutic agent from the tooth. The membrane-forming material may be polymeric or nonpolymeric, ionic or nonionic. The nonionic material may be represented by the formula [R.sup.8 ].sub.b -Si-[R.sup.9 ].sub.4-b, where R.sup.8 may be a hydrocarbon group and may contain heteroatoms selected from nitrogen, sulfur, oxygen, and silicon; R.sup.9 is an alkoxy group containing from 1 to 6, and preferably from 1 to 3, carbon atoms; the value of b is 0, 1, 2 or 3. The only therapeutic agents disclosed by the Chang patents are fluoride salts; these are applied prior to the application of the membrane-forming material. The Chang patents do not appear to suggest that any silicones or any aminoalkyl silicones may be employed to enhance the deposition of a lipophilic compound on the teeth surface. Likewise, the Chang patents do not suggest the co-presence of any silicone and lipophilic compounds in an oil phase of oil-in-water-emulsions.
Thus, the related art discussed above does not provide any oral compositions which include an aminoalkyl silicone and a lipophilic compound in the oil phase of oil-in-water emulsions, or which provide an enhanced deposition of a lipophilic compound on the teeth surface, or which effectively prolong the action of a lipophilic compound in the mouth.
Accordingly, it is an object of the invention to provide oral compositions containing an oil-in-water emulsion, the emulsion including an aminoalkyl silicone and a lipophilic compound in an oil phase and an emulsifier in an aqueous phase.
It is another object of the invention to provide oral compositions containing an oil-in-water emulsion, wherein the emulsion includes an aminoalkyl silicone and a lipophilic antimicrobial in the oil phase and an emulsifier in the aqueous phase.
It is yet another object of the invention to provide oral compositions containing an oil-in-water emulsion, wherein the emulsion includes an aminoalkyl silicone and a lipophilic flavoring or perfuming agent in the oil phase and an emulsifier in the aqueous phase.
It is still another object of the invention to provide a method of preparing an oral composition containing an oil-in-water emulsion, the emulsion including an aminoalkyl silicone and a lipophilic compound in an oil phase and an emulsifier in an aqueous phase.
It is still another object of the invention to provide a method of delivering a lipophilic compound to the teeth surface by applying into an oral cavity a composition containing an oil-in-water emulsion, the emulsion including an aminoalkyl silicone and a lipophilic compound in an oil phase and an emulsifier in an aqueous phase.
These and other objects of the invention will become more apparent from the detailed description and examples which follow.